This is a cooperative clinical study, in conjunction with Stanford University's Division of Radiation Oncology and Division of Urology, to determine the efficacy of regional radiation therapy in the treatment of patients with carcinoma of the prostate. The patient material of the University of California Hospitals and their close affiliates will be added to the ongoing study at Stanford in order to more rapidly complete their study. A recent review at Stanford of the results of long term treatment in 310 patients, who were treated with external, small beam, megavoltage radiation demonstrated 5- and 10-year survival rates of 72% and 48% in disease limited to the prostate and 48% and 27% in disease beyond the prostate. A reasonable explanation for this difference in survival rests on the hypothesis that regional lymph node involvement is likely and important in prognosis. This study is designed to determine the precise degree of involvement which is present as a funciton of the size of the primary tumor and other surgical staging to confirm lymph node status. Patients who have prostatic involvement only will be treated by either local or local plus pelvic irradiation. Patients found to have prostatic plus pelvic node involvement will receive pelvic irradiation with prostatic boost vs. the same with para-aortic prophylactic treatment. Patients whose para-aortic nodes are found to be involved will also receive extended field radiotherapy up to the diaphragm in an attempt to determine whether these nodes remain in any way controllable for a long term. Patients with more distant metastases will be excluded. In addition to evaluating diagnostic pretreatment parameters, the study will also evaluate the ability to transplant these tumors into immunodeficient mice and the response of the tumors to chemotherapeutic agents. Patients developing dissemination will be assessed to determine the influence of reasonable palliative measures.